<template>
  <div class="q-pa-md">
    <div class="text-subtitle1 q-pa-sm">Use <kbd>SHIFT</kbd> to select / deselect a range and <kbd>CTRL</kbd> to add to selection</div>

    <q-table
      flat bordered
      ref="tableRef"
      title="Treats"
      :rows="rows"
      :columns="columns"
      row-key="name"
      selection="multiple"
      v-model:selected="selected"
      @selection="handleSelection"
    >
      <template v-slot:header-selection="scope">
        <q-checkbox v-model="scope.selected" />
      </template>

      <template v-slot:body-selection="scope">
        <q-checkbox :model-value="scope.selected" @update:model-value="(val, evt) => { Object.getOwnPropertyDescriptor(scope, 'selected').set(val, evt) }" />
      </template>
    </q-table>
  </div>
</template>

<script>
import { ref, toRaw, nextTick } from 'vue'

const columns = [
  {
    name: 'name',
    required: true,
    label: 'Dessert (100g serving)',
    align: 'left',
    field: row => row.name,
    format: val => `${ val }`,
    sortable: true
  },
  { name: 'calories', align: 'center', label: 'Calories', field: 'calories', sortable: true },
  { name: 'fat', label: 'Fat (g)', field: 'fat', sortable: true },
  { name: 'carbs', label: 'Carbs (g)', field: 'carbs' },
  { name: 'protein', label: 'Protein (g)', field: 'protein' },
  { name: 'sodium', label: 'Sodium (mg)', field: 'sodium' },
  { name: 'calcium', label: 'Calcium (%)', field: 'calcium', sortable: true, sort: (a, b) => parseInt(a, 10) - parseInt(b, 10) },
  { name: 'iron', label: 'Iron (%)', field: 'iron', sortable: true, sort: (a, b) => parseInt(a, 10) - parseInt(b, 10) }
]

const rows = [
  {
    name: 'Frozen Yogurt',
    calories: 159,
    fat: 6.0,
    carbs: 24,
    protein: 4.0,
    sodium: 87,
    calcium: '14%',
    iron: '1%'
  },
  {
    name: 'Ice cream sandwich',
    calories: 237,
    fat: 9.0,
    carbs: 37,
    protein: 4.3,
    sodium: 129,
    calcium: '8%',
    iron: '1%'
  },
  {
    name: 'Eclair',
    calories: 262,
    fat: 16.0,
    carbs: 23,
    protein: 6.0,
    sodium: 337,
    calcium: '6%',
    iron: '7%'
  },
  {
    name: 'Cupcake',
    calories: 305,
    fat: 3.7,
    carbs: 67,
    protein: 4.3,
    sodium: 413,
    calcium: '3%',
    iron: '8%'
  },
  {
    name: 'Gingerbread',
    calories: 356,
    fat: 16.0,
    carbs: 49,
    protein: 3.9,
    sodium: 327,
    calcium: '7%',
    iron: '16%'
  },
  {
    name: 'Jelly bean',
    calories: 375,
    fat: 0.0,
    carbs: 94,
    protein: 0.0,
    sodium: 50,
    calcium: '0%',
    iron: '0%'
  },
  {
    name: 'Lollipop',
    calories: 392,
    fat: 0.2,
    carbs: 98,
    protein: 0,
    sodium: 38,
    calcium: '0%',
    iron: '2%'
  },
  {
    name: 'Honeycomb',
    calories: 408,
    fat: 3.2,
    carbs: 87,
    protein: 6.5,
    sodium: 562,
    calcium: '0%',
    iron: '45%'
  },
  {
    name: 'Donut',
    calories: 452,
    fat: 25.0,
    carbs: 51,
    protein: 4.9,
    sodium: 326,
    calcium: '2%',
    iron: '22%'
  },
  {
    name: 'KitKat',
    calories: 518,
    fat: 26.0,
    carbs: 65,
    protein: 7,
    sodium: 54,
    calcium: '12%',
    iron: '6%'
  }
]

export default {
  setup () {
    const tableRef = ref()
    const selected = ref([])
    let storedSelectedRow

    return {
      tableRef,
      selected,
      columns,
      rows,

      handleSelection ({ rows, added, evt }) {
        // ignore selection change from header of not from a direct click event
        if (rows.length !== 1 || evt === void 0) {
          return
        }

        const oldSelectedRow = storedSelectedRow
        const [newSelectedRow] = rows
        const { ctrlKey, shiftKey } = evt

        if (shiftKey !== true) {
          storedSelectedRow = newSelectedRow
        }

        // wait for the default selection to be performed
        nextTick(() => {
          if (shiftKey === true) {
            const tableRows = tableRef.value.filteredSortedRows
            let firstIndex = tableRows.indexOf(oldSelectedRow)
            let lastIndex = tableRows.indexOf(newSelectedRow)

            if (firstIndex < 0) {
              firstIndex = 0
            }

            if (firstIndex > lastIndex) {
              [ firstIndex, lastIndex ] = [ lastIndex, firstIndex ]
            }

            const rangeRows = tableRows.slice(firstIndex, lastIndex + 1)
            // we need the original row object so we can match them against the rows in range
            const selectedRows = selected.value.map(toRaw)

            selected.value = added === true
              ? selectedRows.concat(rangeRows.filter(row => selectedRows.includes(row) === false))
              : selectedRows.filter(row => rangeRows.includes(row) === false)
          }
          else if (ctrlKey !== true && added === true) {
            selected.value = [newSelectedRow]
          }
        })
      }
    }
  }
}
</script>
